fix: Connection timeout handling for native clients in connected state (#3512)

Now, when using the native client with a connection timeout, the pool could incorrectly destroy or end a client that was already connected, due to not distinguishing between connection states. This caused issues such as https://github.com/brianc/node-pg-native/issues/49, where a native client that had already established a connection could be forcefully closed if the connection callback was delayed past the timeout.

Co-authored-by: maxbronnikov10 <maxbronnikov2004@gmail.com>